Data communication system, computer, data communication method, and program

ABSTRACT

An object of the present disclosure is to provide a data communication system, a computing apparatus, a data communication method, and a program, which are capable of highly reliable data transfer with low latency between computing apparatuses. The present disclosure achieves a highly reliable communication path by directly connecting computing apparatuses via an optical path and transmitting data through the optical path. Further, the present disclosure uses the optical path to achieve RDAM over wavelength transmission in which existing RDMA-enabled protocol stacks such as InfiniBand and TCP/IP/Ether are eliminated. The present disclosure eliminates the protocol stacks, enabling transfer with lower latency than in a case of “simply performing RDMA transmission over the wavelength path”.

TECHNICAL FIELD

The present disclosure relates to a protocol free technology and aninnovative optical interface technology.

BACKGROUND ART

Data communications between computing apparatus systems use RemoteDirect Memory Access (RDMA) technology for speeding up communicationprocessing (see, for example, Non Patent Literature (NPL) 1 and NPL 2).However, the RDMA technology is designed on the assumption that nosignal loss occurs in communications between computing apparatus systemsand properly operates when no signal loss occurs.

Communications between computing apparatus systems using the RDMAtechnology needs to eliminate the occurrence of packet loss in thenetwork between the computing apparatus systems. For the network, datacommunication via the RDMA technology is given a high priority, andsignals are transferred by controlling preferential process to eliminatethe occurrence of signal loss. For example, data communication signalsare encapsulated by IP, Ethernet (Registered trademark), InfiniBand, orthe like to be given a priority and transferred through the network asIP, Ethernet, or InfiniBand with the priority given (see, for example,NPL 3 and NPL 4).

CITATION LIST Non Patent Literature NPL 1: IETF, “A Remote Direct MemoryAccess Protocol Specification”, RFC 5040, October 2007 NPL 2: IETF,“Remote Direct Memory Access (RDMA) Protocol Extensions”, RFC 7306, June2014 NPL 3: Yibo Zhu et al., “Congestion Control for Large-Scale RDMADeployments”, SIGCOMM 2015, Aug. 17-21, 2015 NPL 4: Hirochika Asai,“Data Center Network for Supporting PFN Distributed Deep LearningInfrastructure MN-2”, Internet Week 2019 Session “Latest Trend of UltraHigh Speed Ultra Low Latency Network”, Nov. 26-29, 2019 NPL 5: KouheiShiomoto, “Outline and Standardization Trend of GMPLS”, pp. 60 - 63, NTTTechnical Journal, April 2004 NPL 6: Satoru Okamoto, “MPLS and GMPLS -Provision of Service and Technology for Supporting Transmission of theSame-”, T19, Internet Week 2006 NPL 7: Open Networking Foundation, “SDNArchitecture for Transport Networks”, ONF TR-522, Mar. 15, 2016 NPL 8:General Incorporated Association: The Telecommunication TechnologyCommittee, “TR-1003, Technical Report on Interface of Optical TransportNetwork (OTN)”, TTC Technical Report, Feb. 20, 2002

NPL 9: General Incorporated Association: The TelecommunicationTechnology Committee, “TR-GSup.39, Optical System Design and EngineeringConsiderations”, TTC technical report, February 10, 2017

NPL 10: ITU-T G.975.1 SUMMARY OF THE INVENTION Technical Problem

Unfortunately, these technologies encapsulate data signals by IP,Ethernet, InfiniBand, or the like to suppress signal loss, andprocessing latency is generated consequently, making it difficult tosufficiently speed up communication processing.

To solve the above problem, an object of the present disclosure is toprovide a data communication system, a computing apparatus, a datacommunication method, and a program, which are capable of highlyreliable data transfer with low latency between computing apparatuses.

Means for Solving the Problem

To achieve the above object, a data communication system according tothe present disclosure directly connects two computing apparatuses via adedicated optical path for optical communication having an errorcorrection function and performs DMR or RDMA transfer via the opticalpath without a signal format of a layer 2 or 3.

Specifically, a data communication system according to the presentdisclosure having two computing apparatuses connected via an opticalpath includes a main storage device that drives an application unithaving data to be transmitted and received between the two computingapparatuses, a light signal physical unit that transmits and receives alight signal frame having an error correction portion with respect tothe optical path, a light signal processing unit that converts the datainto the light signal frame and vice versa, and a direct memory accesscontroller that causes the light signal frame to be transmitted andreceived via the optical path to transfer the data between therespective application unit of the two computing apparatuses by directmemory access or remote direct memory access.

In addition, a computing apparatus according to the present disclosureconnected to another computing apparatus via an optical path includes amain storage device that drives an application unit having data to betransmitted and received between the computing apparatus and the othercomputing apparatus, a light signal physical unit that transmits andreceives a light signal frame having an error correction portion withrespect to the optical path, a light signal processing unit thatconverts the data into the light signal frame and vice versa, a directmemory access controller that causes the light signal frame to betransmitted and received via the optical path to transfer the databetween the respective application unit of the computing apparatus andthe other computing apparatus by direct memory access or remote directmemory access.

Further, a data communication method according to the present disclosurein a data communication system having two computing apparatusesconnected via an optical path includes driving an application unithaving data to be transmitted and received between the two computingapparatuses, transmitting and receiving a light signal frame having anerror correction portion with respect to the optical path, convertingthe data into the light signal frame and vice versa, and transmittingand receiving the light signal frame via the optical path to transferthe data between the respective application unit of the two computingapparatuses by direct memory access or remote direct memory access.

The present data communication system eliminates upper protocols (suchas IP/Ethernet/InfiniBand) used in the known RDMA, enabling datacommunication with low latency. In addition, connecting the twocomputing apparatuses via the optical path does not cause packet lossdue to conflicts, and the communication adopts an error correctionscheme, enabling a highly reliable system.

That is, the present disclosure includes an error correction functionand uses a light signal with reduced packet loss as an RMDA signal,which is considerably affected by the packet loss, thus enabling ahighly reliable system.

Therefore, the present disclosure may provide a data communicationsystem, a computing apparatus, a data communication method, and aprogram, which are capable of highly reliable data transfer with lowlatency between computing apparatuses.

The data communication system according to the present disclosurefurther includes an optical switch that establishes the optical path.Setting the optical path for the optical switch further improves thereliability because no conflict of the light signal occurs.

The data communication system according to the present disclosurefurther includes an optical path controller that controls the connectionof the optical switch and establishes and deletes the optical path. Acounterpart for which the optical path is set can be switched.

The present disclosure is a program for causing a computer to operate asthe computing apparatus. The computing apparatus according to thepresent disclosure may also be implemented by a computer and a program,and the program may also be recorded in a recording medium and providedthrough a network.

Each aspect of the disclosures described above can be combined as muchas possible.

Effects of the Invention

The present disclosure may provide a data communication system, acomputing apparatus, a data communication method, and a program, whichare capable of highly reliable data transfer with low latency betweencomputing apparatuses.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram for explaining a data communication system accordingto the present disclosure.

FIG. 2 is a diagram for explaining a data communication system accordingto the present disclosure.

FIG. 3 is a diagram for explaining an effect of a data communicationsystem according to the present disclosure.

FIG. 4 is a diagram for explaining an effect of a data communicationsystem according to the present disclosure.

FIG. 5 is a diagram for explaining a data communication system accordingto the present disclosure.

FIG. 6 is a diagram for explaining a data communication system accordingto the present disclosure.

FIG. 7 is a diagram for explaining a data communication method accordingto the present disclosure.

FIG. 8 is a diagram for explaining a data communication system accordingto the present disclosure.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described with referenceto the accompanying drawings. The embodiments described below areexamples of the present disclosure and the present disclosure is notlimited to the embodiments described below. Note that constituentelements with the same reference signs in the specification and thedrawings are assumed to be the same constituent elements.

Overview

It is common to use RDMA as high speed data communication between twocomputing apparatuses. Because RDMA requires a highly reliablecommunication path with no packet loss, it is necessary to use RDMA onTCP having a retransmission function or on priority-controlledIP/Ethernet, so as to secure reliability.

The present disclosure achieves a highly reliable communication path bydirectly connecting computing apparatuses via an optical path andtransmitting data through the optical path. Further, the presentdisclosure achieves RDAM over wavelength transmission in which existingRDMA-support protocol stacks such as InfiniBand, TCP/IP/Ether and thelike are eliminated by utilizing the optical path. The presentdisclosure may achieve transfer with lower latency than in a case of“simply performing RDMA transmission over the wavelength path”, byeliminating the protocol stacks. Hereinafter, the invention will bedescribed with reference to a specific data communication system.

First Embodiment

FIG. 1 is a diagram for explaining a data communication system 301 ofthe present embodiment. The data communication system 301 having twocomputing apparatuses (10-1 and 10-2) connected via an optical path 50includes a main storage device 11 that drives an application unit 11 ahaving data to be transmitted and received between the two computingapparatuses, a light signal physical unit 16 that transmits and receivesa light signal frame having an error correction portion with respect tothe optical path 50, a light signal processing unit 15 that converts thedata into the light signal frame and vice versa, and a direct memoryaccess controller 14 that causes the light signal frame to betransmitted and received via the optical path 50 and causes the data tobe transferred between an application unit of a computing apparatus ofthe two computing apparatuses and an application unit of anothercomputing apparatus of the two computing apparatuses by direct memoryaccess or remote direct memory access.

The data communication system 301 connects the computing apparatuses 10to each other with the optical path 50, in which no packet loss issubstantially generated. The optical path 50 is, for example, an OpticalData Unit (ODU) defined by ITU-T G.709, and the ODU is a signal that isprovided with at least one error correcting signal and is transmittedbetween terminating points (see, for example, NPL 8 and NPL 9). Examplesof the setting and deletion of the optical path 50 and the control ofthe light signal frame transmission include a distributed control modelsuch as Generalized Multi Protocol Label Switching (GMPLS) (see, forexample, NPL 5 and NPL 6), or a centralized control model such asSoftware Defined Network (SDN), Network Management System (NMS)/ElementManagement System (EMS) or the like (see, for example, NPL 7).

The computing apparatuses (10-1 and 10-2) each include the main storagedevice 11 configured to store the application unit 11 a and an operatingsystem 11 b, a CPU 12 equipped with a cache 12 a configured to drivepart of or all of the application unit 11 a, an external storage device13, the direct memory access controller 14, and the light signalphysical processing unit 16.

The computing apparatus 10-1 and the computing apparatus 10-2communicate light signal frames with error correction functions via therespective light signal physical processing units 16. At this time, thecomputing apparatuses (10-1 and 10-2) perform the direct memory accesstransfer not through the signal format of the layer 2 or layer 3 such asIP, Ethernet, InfiniBand or the like on the light signal.

The computing apparatuses (10-1 and 10-2) each further include the lightsignal processing unit 15 and the application unit 11 a to be driven onthe main storage device 11. The light signal processing unit 15 is, forexample, an Optical Data Unit (ODU) interface.

The direct memory access transfer or remote direct memory accesstransfer by the DMA controller 14 is performed between the applicationunit 11 a of the computing apparatus 10-1 and the application unit 11 aof the computing apparatus 10-2.

The application unit 11 a has a function of transmitting and receivingdata to and from the light signal processing unit 15. The light signalprocessing unit 15 has a function of transmitting and receiving data toand from the application unit 11 a, a function of converting datareceived from the application unit 11 a into a light signal frame andtransmitting the light signal frame to the light signal physicalprocessing unit 16, and a function of receiving a light signal framefrom the light signal physical processing unit 16 and extracting datatherefrom.

FIG. 2 is a diagram for explaining a data flow when the datacommunication system 301 performs a direct memory access transfer. Inthis example, an example of transferring data from the computingapparatus 10-2 to the computing apparatus 10-1 will be described.

Data of the application unit 11 a of the computing apparatus 10-2 isaccumulated in the cache 12 a or in the application unit 11 a of themain storage device 11. A file of the application unit 11 a is stored inthe external storage device 13, and when executed, the file is firstdeployed on the main storage device 11. Part of the application unit 11a is stored in the cache 12 a of the CPU in such a manner that highspeed processing by the CPU is achieved. The DMA controller 14 of thecomputing apparatus 10-2 reads the data in the cache 12 a (DMA Read) andmoves the read data to the light signal processing unit 15 of thecomputing apparatus 10-2 in order to transfer it to the computingapparatus 10-1 (RDMAS Send). The light signal processing unit 15converts the above data into a light signal frame. An error correctingcode is also assigned to the light signal frame. The light signalphysical processing unit 16 of the computing apparatus 10-2 transmitsthis light signal frame to the optical path 50.

The light signal physical processing unit 16 of the computing apparatus10-1 receives the above light signal frame from the optical path 50.Subsequently, the light signal processing unit 15 of the computingapparatus 10-1 converts the signal frame into data. The DMA controller14 of the computing apparatus 10-1 confirms that the data is the onefrom the computing apparatus 10-2 (RDMA Receive), and then delivers thedata to the main storage device 11 of the computing apparatus 10-1 (DMAWrite). As described above, the application unit 11 a of the computingapparatus 10-1 receives the data.

Thus, the data communication system 301 converts the data directly intoa light signal frame and carries out the data transfer by RDMA using theoptical path 50. By carrying out the data transfer using the opticalpath 50, data loss between the computing apparatuses 10 is suppressed.The data communication system 301 achieves the RDMA transfer whileavoiding the encapsulation of data in the IP, Ethernet, InfiniBand, orthe like, in which processing latency occurs, by directly converting thedata into the light signal frame.

The data communication system 301 may reduce layers because of noencapsulation being made. In the data communication system 301, forexample, the function of a signal-synchronization signal such as apreamble mounted in a light signal of ODU or the like, and the functionof a signal-synchronization signal such as a preamble mounted in alayer-2 signal of Ethernet or the like are redundant due to the layerelimination, so that the signal synchronization processing functions mayalso degenerate into the one on the light signal side only. Because ofthis, the data communication system 301 may reduce processing latency atthe start of communication.

It is possible for the data communication system 301 to prevent thegeneration of packet loss in the communications between the computingapparatuses 10 by two points as follows.

(1) By directly connecting the computing apparatuses 10 with the opticalpath, packet loss due to conflicts does not occur.More specific description will be made. First, an optical path isconstituted by setting an optical switch or the like by signaling beforethe start of communication with a main signal. The optical path is in astate in which a start point and a termination point are fixedlyconnected. Because of this, a main signal of another optical path havinga start point and a termination point different from those describedabove does not overlap the optical path. With this, in the opticaltransmission system using the optical path, a packet loss caused by abuffer shortage because of scrambling for the same buffer region withina group of packets whose output destinations are the same does not occurin principle, unlike in a packet communication system.(2) By assigning an error correcting code (FEC) to a light signal frame,a bit error rate (BER) is significantly improved. FIG. 3 is a diagram inwhich a BER in a case of the error correcting code being assigned to alight signal frame and a BER in a case of the error correcting codebeing not assigned to a light signal frame are compared. By assigningthe error correcting code to the light signal frame, the BER may beimproved by two or more orders of magnitude compared to the case of notassigning the error correcting code. The error correcting code may beapplied to the light signal multiple times. In a case of using OTNStandard FEC (GFEC) defined in ITU-T G.975, the BER may be improved byfive or more orders of magnitude as depicted in FIG. 4 . SDH in band FECand OTN Enhanced FEC (EFEC) are also defined in ITU-T G.975 (see, forexample, NPL 10).

In the present embodiment, the optical path has been described as anODU, but the optical path is not limited thereto. The optical path maynot be the ODU as long as the light signal with an error correctionfunction assigned is used.

Second Embodiment

FIG. 5 is a diagram for explaining a data communication system 302 ofthe present embodiment. The data communication system 302 furtherincludes an optical switch 51 configured to establish the optical path50 with respect to the data communication system 301 of FIG. 1 . Thatis, a feature of the data communication system 302 is such that at leastone optical switch 51 is disposed between the computing apparatus 10-1and the computing apparatus 10-2, and a light signal frame between thecomputing apparatus 10-1 and the computing apparatus 10-2 passes throughthe optical switch 51.

Because the data communication system 302 sets the optical path betweenthe computing apparatus 10-1 and the computing apparatus 10-2 via theoptical switch 51, the computing apparatus 10-1 may also set an opticalpath between the computing apparatus 10-1 and a computing apparatus10-3, for example, by changing the setting of the optical switch 51.Further, as illustrated in FIG. 5 , by the setting of the optical switch51, the optical path is set between the computing apparatus 10-1 and thecomputing apparatus 10-2, and an optical path may also be set betweenthe computing apparatus 10-3 and a computing apparatus 10-4.

The following two points are causes for a decrease in transfer rate ofRDMA.

(1) Bit error(2) Output buffer shortage in packet switch systems such as IP routers,Ethernet switches, infiniBand switches and the likeThis causes the conflicts to occur at the output destination of thepacket group.

The cause (1) may be resolved by OTN error correction.

As for the cause (2), in a case where a plurality of server-clientcommunications are generated in a packet switch network, packetconflicts occur in a probabilistic manner. Thus, in the presentembodiment, the optical switch 51 is employed in such a manner thatpacket conflicts do not occur in principle. The packet conflicts do notoccur in principle as long as the optical switch 51 has succeeded inestablishing the optical path. In addition, because the optical switchchanges an input port and an output port by a mirror like a mirror type,a high level of processing such as reading a header like an IP packet isunnecessary, so that a reduction in transfer rate caused by the aboveprocessing can be prevented.

Third Embodiment

FIG. 6 is a diagram for explaining a data communication system 303 ofthe present embodiment. The data communication system 303 furtherincludes, with respect to the data communication system 302 of FIG. 5 ,optical path controllers 11 c configured to control the connection ofthe optical switch 51 and establish and delete the optical path 50. Thatis, the data communication system 303 includes computing apparatuses(10-1 and 10-2) each including the optical path controller 11 cexchanges an optical path control message between the computingapparatuses (10-1 and 10-2), and dynamically set or delete the opticalpath 50.

The data communication system 303 utilizes the optical path controller11 c to dynamically change an input port and an output port of theoptical switch 51. This function allows the data communication system303 to set the optical path between the computing apparatus 10-1 and thecomputing apparatus 10-2, and also set an optical path between thecomputing apparatus 10-1 and the computing apparatus 10-3. The opticalpath controller 11 c may be achieved by the technologies described inNPL 5 to NPL 7.

Fourth Embodiment

FIG. 7 is a diagram for explaining a data communication method in thedata communication systems 301 to 303 described above. The present datacommunication method includes driving the application unit 11 a havingdata to be transmitted and received between the computing apparatuses(10-1 and 10-2) (step S01), transmitting and receiving a light signalframe having an error correction portion with respect to the opticalpath 50 (step S02), converting the data into the light signal frame andvice versa (step S03), and transmitting and receiving the light signalframe via the optical path 50 to transfer the data between theapplication unit of the computing apparatus and an application unit ofthe other computing apparatus by direct memory access or remote directmemory access (step S04).

In the computing apparatus 10 on the transmission side, the light signalprocessing unit 15 converts data into the light signal frame (step S03).Subsequently, in the computing apparatus 10 on the transmission side,the light signal physical processing unit 16 transmits the light signalframe to the optical path 50 (step S02). On the other hand, in thecomputing apparatus 10 on the reception side, the light signal physicalprocessing unit 16 receives the light signal frame from the optical path50 (step S02). Subsequently, in the computing apparatus 10 on thereception side, the light signal processing unit 15 converts the lightsignal frame into data (step S03). Then, the application unit 11 a ofthe computing apparatus 10 on the reception side receives the data andperforms data processing (step S01). In this case, step S02 and step S03are the direct memory access transfer or remote direct memory accesstransfer by the DMA controller 14 (step S04).

The setting of the optical path 50 is made in the following manner. Inthe case of a GMPLS control network, a transmission source (start point)and a transmission destination (termination point) are determined, andthen a relay route is determined by IP routing. Thereafter, the opticalpath controller 11 c performs signaling for setting the optical switch51 from the start point to the termination point (start point,termination point, relay point). By this signaling, the optical switch51 serves to change or connect an input port and an output port so as tobuild the optical path 50.

Fifth Embodiment

The computing apparatus 10 may also be implemented by a computer and aprogram, and the program may also be recorded in a recording medium andprovided through a network.

FIG. 8 is a block diagram illustrating a system 100. The system 100includes a computer 105 connected to a network 135.

The network 135 is a data communication network. The network 135 may bea private network or a public network and can include any one of (a) apersonal area network covering a certain room, for example, (b) a localarea network covering a certain building, for example, (c) a campus areanetwork covering a certain campus, for example, (d) a metropolitan areanetwork covering a certain city, for example, (e) a wide area networkcovering areas being connected across boundaries of urban areas, ruralareas, or nations, for example, or (f) the Internet, or all of them. Thecommunication is performed by electronic signals and light signals viathe network 135.

The computer 105 includes a processor 110 and a memory 115 connected tothe processor 110. Although the computer 105 is represented herein as astandalone device, it is not so limited, but rather may be connected toother devices not illustrated in a distributed processing system.

The processor 110 is an electronic device configured with logiccircuitry that responds to and executes instructions.

The memory 115 is a storage medium readable to a tangible computer witha computer program encoded therein. In this regard, the memory 115stores data and instructions, that is, a program code, readable andexecutable by the processor 110 to control operation of the processor110. The memory 115 can be implemented in a random access memory (RAM),a hard drive, a read-only memory (ROM), or a combination thereof. One ofconstituent elements of the memory 115 is a program module 120.

The program module 120 includes instructions for controlling theprocessor 110 to execute the processes described herein. Althoughoperations are described herein as being performed by the computer 105or a method or a process or a sub-process thereof, the operations areactually performed by the processor 110.

The term “module” is used herein for referring to a functional operationthat can be embodied as either a stand-alone constituent element or anintegrated configuration of a plurality of lower constituent elements.Thus, the program module 120 may be achieved as a single module or as aplurality of modules that operate in cooperation with one another.Moreover, while the program module 120 is described herein as beinginstalled in the memory 115 and thus achieved in software, it is alsopossible to be achieved in any of hardware (for example, electroniccircuit), firmware, software, or a combination thereof.

Although the program module 120 is illustrated as already being loadedinto the memory 115, it may be configured to be located on a storagedevice 140 so as to be later loaded into the memory 115. The storagedevice 140 is a storage medium readable to a tangible computer storingthe program module 120. Examples of the storage device 140 include acompact disc, a magnetic tape, a read-only memory, an optical storagemedium, a memory unit composed of a hard drive or a plurality ofparallel hard drives, and a universal serial bus (USB) flash drive.Alternatively, the storage device 140 may be a random access memory oranother type of electronic storage device that is located in a remotestorage system not illustrated and is connected to the computer 105 viathe network 135.

The system 100 further includes a data source 150A and a data source150B collectively referred to as a data source 150 herein andcommunicatively connected to the network 135. In practice, the datasource 150 can include any number of data sources, that is, one or moredata sources. The data source 150 can include unstructured data andinclude social media.

The system 100 further includes a user device 130 operated by a user 101and connected to the computer 105 via the network 135. The user device130 includes an input device, such as a keyboard, speech recognitionsubsystem or the like, for enabling the user 101 to transmit informationand a selection of commands to the processor 110. The user device 130further includes an output device, such as a display device, a printer,an audio synthesizer or the like. A cursor control unit, such as amouse, a trackball, a touch sensitive screen or the like, allows theuser 101 to manipulate the cursor on the display device to transmitadditional information and a selection of commands to the processor 110.

The processor 110 outputs a result 122 of execution of the programmodule 120 to the user device 130. Alternatively, the processor 110 canprovide output to a storage device 125, such as a database, a memory orthe like, or can provide output to a remote device not illustrated viathe network 135.

For example, a program for carrying out the flowchart of FIG. 7 may bethe program module 120. The system 100 may be operated as the computingapparatus 10.

The term “includes”, “including”, “comprises”, or “comprising” specifiesthat features, integers, steps, or constituent elements describedtherein are present, but it should be interpreted that the term does notexclude the presence of one or more other features, integers, steps, orconstituent elements, or the presence of groups thereof. The terms “a”and “an” are indefinite articles and thus do not exclude embodimentshaving a plurality of constituent elements.

Other Embodiments

Note that the present disclosure is not limited to the above-describedembodiments and can be variously modified and implemented within thescope not departing from the gist of the present disclosure. In short,the present disclosure is not limited to the higher-level embodiment asit is, and can be embodied, at the implementation stage, with theconstituent elements modified within the scope not departing from thegist thereof.

Various inventions can be formed by appropriate combinations of aplurality of constituent elements disclosed in the above-describedembodiments. For example, several constituent elements may be omittedfrom all the constituent elements illustrated in the embodiments.Furthermore, constituent elements in different embodiments may beappropriately combined with each other.

REFERENCE SIGNS LIST

10, 10-1 to 10-4: Computing apparatus11: Main storage device11 a: Application unit11 b: Operating system11 c: Optical path controller

12: CPU 12 a: Cache

13: External storage device14: Direct memory access controller15: Light signal processing unit16: Light signal physical processing unit50: Optical path51: Optical switch

100: System 101: User 105: Computer 110: Processor 115: Memory

120: Program module

122: Result

125: Storage device130: User device

135: Network

140: Storage device150: Data source

1. A data communication system having two computing apparatusesconnected via an optical path, the data communication system comprising:a main storage device configured to drive an application unit havingdata to be transmitted and received between the two computingapparatuses; a light signal physical unit configured to transmit andreceive a light signal frame having an error correction portion withrespect to the optical path; a light signal processing unit configuredto convert the data into the light signal frame and vice versa; and adirect memory access controller configured to cause the light signalframe to be transmitted and received via the optical path to transferthe data between the respective application unit of the two computingapparatuses by direct memory access or remote direct memory access. 2.The data communication system according to claim 1, further comprisingan optical switch configured to establish the optical path.
 3. The datacommunication system according to claim 2, further comprising an opticalpath controller configured to control connection of the optical switchand establish and delete the optical path.
 4. A computing apparatusconnected to another computing apparatus via an optical path, thecomputing apparatus comprising: a main storage device configured todrive an application unit having data to be transmitted and receivedbetween the computing apparatus and the other computing apparatus; alight signal physical unit configured to transmit and receive a lightsignal frame having an error correction portion with respect to theoptical path; a light signal processing unit configured to convert thedata into the light signal frame and vice versa; and a direct memoryaccess controller configured to cause the light signal frame to betransmitted and received via the optical path to transfer the databetween the respective application unit of the computing apparatus andthe other computing apparatus by direct memory access or remote directmemory access.
 5. A data communication method in a data communicationsystem having two computing apparatuses connected via an optical path,the data communication method comprising: driving an application unithaving data to be transmitted and received between the two computingapparatuses; transmitting and receiving a light signal frame having anerror correction portion with respect to the optical path; convertingthe data into the light signal frame and vice versa; and transmittingand receiving the light signal frame via the optical path to transferthe data between the respective application unit of the two computingapparatuses by direct memory access or remote direct memory access.
 6. Anon-transitory computer-readable medium storing a program for causing acomputer to operate as the computing apparatus according to claim 4.